1. Technical Field
The present invention relates to a liquid ejecting head such as an ink jet recording head and a liquid ejecting apparatus and, more specifically, to a liquid ejecting head including a holding member provided with a head unit configured to eject liquid from a nozzle, a wiring member configured to be electrically connected to pressure generating units, and a wiring substrate configured to supply drive signals to the pressure generating units through the wiring member, and a liquid ejecting apparatus.
2. Related Art
A liquid ejecting apparatus is an apparatus including a liquid ejecting head, and configured to eject various types of liquid from the liquid ejecting head. Examples of a liquid ejecting apparatus include image recording apparatuses such as ink jet printers and ink jet plotters. However, in recent years, liquid ejecting apparatuses have also been applied to various types of manufacturing apparatuses by taking advantage of property that an extremely small amount of liquid is dropped accurately on a predetermined position. For example, the invention can be applied to display manufacturing apparatuses configured to manufacture color filters such as liquid crystal displays, electrode forming apparatuses configured to form electrodes such as those of organic electro luminescence displays, FEDs (surface emitting displays), and chip manufacturing apparatuses configured to manufacture biochips (biochemical elements). A recording head for image recording apparatuses ejects liquid ink, and a color material ejecting head for display manufacturing apparatuses ejects liquid solutions of respective color materials of R (Red), G (Green), and B (Blue). An electrode material ejecting head for an electrode forming apparatuses ejects a liquid electrode material and a bioorganic substance ejecting head for a chip manufacturing apparatuses ejects a liquid solution of bioorganic substance.
There are various types of liquid ejecting heads as described above, and those employing a so-called on-demand system which is in widespread use include a series of liquid flow channels, provided in a plurality, extending from a common liquid chamber (also referred to as a reservoir or a manifold) via pressure chambers to nozzles so as to correspond to nozzles, and are configured, for example, to eject liquid droplets from the nozzles by using pressure variations generated in the liquid in the pressure chambers by driving pressure generating units such as piezoelectric elements or heat generating elements.
A supply flow channel to which liquid from a liquid supply source such as an ink cartridge is supplied communicates with the common liquid chamber. The supply flow channel is located at a center portion of the common liquid chamber in the longitudinal direction, and is configured in such a manner that the distance from a communicating point (introduction port) between the supply flow channel and the common liquid chamber to the pressure chamber located at the farthest position from the introduction port from among the respective pressure chambers communicating with the common liquid chamber is as small as possible (that is, the distance is approximately half the dimension of the common liquid chamber in the longitudinal direction) (for example, see JP-A-2010-023437 (FIG. 2, and so forth). Accordingly, pressures of ink supplied to the respective pressure chamber communicating the same common liquid chamber are prevented from becoming unbalanced.
Incidentally, examples of a liquid ejecting head of this type include a liquid ejecting head provided on a case member (holding member), the liquid ejecting head including a wiring substrate (printed board) configured to receive a drive signal from an apparatus body side and supply the received drive signal to the pressure generating units, and the drive signal is supplied from the wiring substrate to the respective pressure generating units through a wiring member having flexibility (hereinafter, referred to as a flexible cable) such as a COP (chip on film) or TCP (tape carrier package). The flexible cable has a configuration in which a conductive pattern is formed on a surface of, for example, a base film such as polyimide using copper foil or the like, and the conductive pattern is covered with resist. A terminal portion on one end of the flexible cable is connected to a terminal portion of the pressure generating unit, and a terminal portion on the other end is connected to a base terminal portion on the wiring substrate.
The flexible cable is wired in a limited space in a recording head (in the case member). In particular, in the configuration in which the supply flow channel is connected to the center portion of the common liquid chamber, wiring of the flexible cable that bypasses the supply flow channel or provision of a clearance hole configured to allow passage of the supply flow channel of the flexible cable is needed. In the former case, in a configuration in which the length of the flexible cable is fixed to a certain length because of a layout or the like of the conductive pattern, it is necessary to wire the flexible cable along the direction of the height of the case member in order to avoid interference with respect to the supply flow channel, and hence the case member is required to have a height that correspondingly depends on the length of the flexible cable. Therefore, there is a problem of an increase in the size of the recording head. In the latter case, when the clearance hole as described above is formed in the flexible cable, formation of a conductive pattern on the flexible cable that bypasses the clearance hole is necessary. Therefore, there is a problem of an increase in the size of the flexible cable and an increase in cost. In the same manner, in the latter configuration, formation of the clearance hole configured to allow passage of the supply flow channel in the wiring substrate is needed, and hence the cost is increased in association with increase in the size of the wiring substrate in this aspect as well.